Katherine Reyes

Trends in US hospital admissions for skin and soft tissue infections.

Using data from the 2000–2004 US Healthcare Cost and Utilization Project National Inpatient Sample, we found that total hospital admissions for skin and soft tissue infections increased by 29% during 2000–2004; admissions for pneumonia were largely unchanged. These results are consistent with recent reported increases in community-associated methicillin-resistant Staphylococcus aureus infections.

Relationship of Vancomycin Minimum Inhibitory Concentration to Mortality in Patients With Methicillin-Resistant Staphylococcus aureus Hospital-Acquired, Ventilator-Associated, or Health-care-Associated Pneumonia

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP), and health-care-associated pneumonia (HCAP). These infections are associated with significant morbidity, mortality, and cost. The impact of vancomycin minimum inhibitory concentration (MIC) on mortality for patients with MRSA pneumonia has not been determined. METHODS Adult patients in ICUs with a diagnosis of MRSA HAP, VAP, or HCAP were entered in the study. Clinical and laboratory information were prospectively collected. Vancomycin MIC and heteroresistance were determined for each MRSA isolate. Data were collected from February 2006 through August 2007. The primary outcome variable was all-cause mortality at day 28. A propensity score approach was used to adjust for confounding variables. RESULTS The study sample consisted of 158 patients. All-cause mortality at day 28 was 32.3%. The majority of MRSA isolates had a vancomycin MIC ≥ 1.5 mg/mL (115/158, 72.8%). Propensity score analysis demonstrated an increase in 28-day mortality as vancomycin MIC increased from 0.75 to 3 mg/mL (P ≤ .001). Heteroresistance to vancomycin, demonstrated in 21.5% isolates, was not associated with mortality. CONCLUSIONS Mortality in patients with MRSA HAP, VAP, and HCAP increases as a function of the vancomycin MIC, even for strains with MIC values within the susceptible range. Evaluation of vancomycin MICs should be contemplated at the institutional level and for individual cases of MRSA pneumonia. The use of vancomycin therapy in patients with MRSA pneumonia caused by isolates with MICs between 1 and 2 mg/mL should be undertaken with caution, and alternative therapies should be considered.

Characterization of Vancomycin-Resistant Enterococcus faecium Isolated from Swine in Three Michigan Counties

ABSTRACT Vancomycin-resistant enterococci are a major cause of nosocomial infections but are rarely found in humans in the community and have not been identified in food animals in the United States. We evaluated a total of 360 fecal specimens from humans and their animals being raised for exhibit at three county fairs in Michigan. Fecal samples from 158 humans, 55 swine, 50 cattle, 25 horses, 57 sheep, 14 goats, and 1 llama were obtained and plated onto Enterococcosel agar containing 16 μg/ml of vancomycin. Vancomycin-resistant Enterococcus faecium (VREF) was isolated from six pigs but not from humans or any animal other than pigs. All six VREF isolates had a MIC to vancomycin of ≥256 μg/ml and contained the vanA gene. Pulsed-field gel electrophoresis (PFGE) patterns of the six VREF isolates were ≥80% similar. Multilocus sequence typing (MLST) revealed sequence type 5 (ST5) (n = 2), ST6 (n = 3), and ST185 (n = 1), which are E. faecium sequence types belonging to clonal complex 5 (CC5). These findings show the dissemination of VREF strains among pigs in three Michigan counties. This is the first report of VRE found in food animals in the United States.

Clinical Outcomes of Daptomycin for Vancomycin-resistant Enterococcus Bacteremia

PURPOSE In light of recent evidence suggesting enhancement of daptomycin activity against vancomycin-resistant Enterococcus (VRE) by ampicillin and other β-lactam antibiotics, we evaluated the safety profile and clinical efficacy of daptomycin with and without concomitant β-lactam antimicrobials in the treatment of VRE (faecium or faecalis) bacteremia from multiple centers across the United States. METHODS Data were collected retrospectively as part of a larger multicenter registry (The Cubicin Outcomes Registry and Experience). Efficacy and clinical outcomes in patients with VRE bacteremia who received at least 3 days of daptomycin with or without concomitant β-lactams were analyzed. Although all the cases involved daptomycin-susceptible VRE, additional analysis was performed to examine whether the adjunctive β-lactam would play a more pivotal role in cases where the daptomycin MIC was in the upper limit of the susceptibility range, indicating that daptomycin monotherapy efficacy may be relatively compromised compared with cases with lower daptomycin MICs. FINDINGS Two hundred sixty-two patients from 33 hospitals were evaluated. Most patients had at least one significant comorbidity, such as solid-organ or bone marrow transplantation (16%), neutropenia (36%), dialysis dependency (20%), or critical illness (36%) requiring care in an intensive care unit. Overall treatment success was 86% (n = 225/262), and treatment success for patients taking concomitant β-lactams was 86% (n = 105/122). Logistic regression identified treatment failure to be associated with sepsis (odds ratio = 3.42; P = 0.009) and an elevated daptomycin MIC (3-4 µg/mL) (odds ratio = 3.23, P = 0.013). No significant increase in clinical failure was seen among patients with elevated daptomycin MIC who received concomitant β-lactam therapy (clinical success, 88% vs 79% for MIC ≤2 vs 3-4 µg/mL, respectively; P = 0.417). Of 262 patients, 33 (13%) experienced ≥1 adverse event possibly related to daptomycin (increased creatine kinase in 8 patients). IMPLICATIONS Overall, daptomycin was effective and well tolerated for VRE bacteremia, with lower effectiveness noted with daptomycin MIC of 3 to 4 µg/mL. Concomitant β-lactam therapy with daptomycin may improve clinical outcomes in this setting. Further studies are needed to characterize the potential benefit of concomitant β-lactams with daptomycin.

Evaluation of Risk Factors for Coinfection or Cocolonization with Vancomycin-Resistant Enterococcus and Methicillin-Resistant Staphylococcus aureus

ABSTRACT We retrospectively evaluated 410 patients with coinfection or cocolonization due to vancomycin-resistant (VR) enterococcus (VRE) and methicillin-resistant Staphylococcus aureus (MRSA). The prevalence rate was 19.8%. Risk factors included isolation of VR Enterococcus faecalis and use of linezolid or clindamycin. Inc18-like vanA plasmids were found in 7% of VR E. faecalis isolates and none of the VR E. faecium isolates.

Comparative Effectiveness of Vancomycin Versus Daptomycin for MRSA Bacteremia With Vancomycin MIC >1 mg/L: A Multicenter Evaluation

PURPOSE Clinical studies comparing vancomycin with alternative therapy for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia are limited. The objective of this study was to compare outcomes of early daptomycin versus vancomycin treatment for MRSA bacteremia with high vancomycin MICs in a geographically diverse multicenter evaluation. METHODS This nationwide, retrospective, multicenter (N = 11), matched, cohort study compared outcomes of early daptomycin with vancomycin for MRSA bloodstream infection (BSI) with vancomycin MICs 1.5 to 2 µg/mL. Matching variables, based on propensity regression analysis, included age, intensive care unit (ICU), and type of BSI. Outcomes were as follows: (1) composite failure (60-day all-cause mortality, 7-day clinical or microbiologic failure, 30-day BSI relapse, or end-of-treatment failure (EOT; discontinue/change daptomycin or vancomycin because of treatment failure or adverse event]); (2) nephrotoxicity; and (2) day 4 BSI clearance. FINDINGS A total of 170 patients were included. The median (interquartile range) age was 60 years (50-74); the median (range) Acute Physiology and Chronic Health Evaluation II score was 15 (10-18); 31% were in an ICU; and 92% had an infectious disease consultation. BSI types included endocarditis/endovascular (39%), extravascular (55%), and central catheter (6%). The median daptomycin dose was 6 mg/kg, and the vancomycin trough level was 17 mg/L. Overall composite failure was 35% (59 of 170): 15% due to 60-day all-cause mortality, 14% for lack of clinical or microbiologic response by 7 days, and 17% due to failure at end of therapy (discontinue/change because of treatment failure or adverse event). Predictors of composite failure according to multivariate analysis were age >60 years (odds ratio, 3.7; P < 0.01) and ICU stay (odds ratio, 2.64; P = 0.03). Notable differences between treatment groups were seen with: (1) end of therapy failure rates (11% vs 24% for daptomycin vs vancomycin; P = 0.025); (2) acute kidney injury rates (9% vs 23% for daptomycin vs vancomycin; P = 0.043); and (3) day 4 bacteremia clearance rates for immunocompromised patients (n = 26) (94% vs 56% for daptomycin vs vancomycin; P = 0.035). IMPLICATIONS Results from this multicenter study provide, for the first time, a geographically diverse evaluation of daptomycin versus vancomycin for patients with vancomycin-susceptible MRSA bacteremia with vancomycin MIC values >1 µg/mL. Although the overall composite failure rates did not differ between the vancomycin and daptomycin groups when intensively matched according to risks for failure, the rates of acute kidney injury were significantly lower in the daptomycin group. These findings suggest that daptomycin is a useful therapy for clinicians treating patients who have MRSA bacteremia. Prospective, randomized trials should be conducted to better assess the potential significance of elevated vancomycin MIC.

Risk factors for quinolone-resistant Escherichia coli urinary tract infection

Background:Escherichia coli is the leading cause of urinary tract infections (UTI). Current Infectious Diseases Society of America (IDSA) guidelines recommend the use of fluoroquinolones when resistance to trimethoprim-sulfamethoxazole is greater than 10% to 20%. Identification of risk factors for fluoroquinolone-resistant E. coli may provide information to help in choosing the optimal empiric treatment of patients with UTI. Objective:To identify risk factors for fluoroquinolone-resistant E. coli in patients with UTI. Methods:Retrospective case control study of UTI caused by quinolone-resistant E. coli. Results:Risk factors for fluoroquinolone-resistant E. coli UTI included recurrent UTI (odds ratio [OR], 2.28; P = 0.017), underlying medical disease (OR, 5.28; P < 0.001), urinary tract abnormalities (OR, 2.99; P = 0.002), prior hospitalization within the last 6 months (OR, 5.58; P = 0.032) and prior treatment with antibiotics within the last 6 months (OR, 13.72; P < 0.001). Isolates were susceptible to nitrofurantoin (94.9%), cepholosporins (79.7%), aminoglycosides (amikacin 97.5%, gentamicin 75.9%), and imipenem (98.7%). Conclusions:Fluoroquinolones should be used with caution in patients with UTI and risk factors for fluoroquinolone-resistant E. coli.

Human Cathelicidin LL-37 Resistance and Increased Daptomycin MIC in Methicillin-Resistant Staphylococcus aureus Strain USA600 (ST45) Are Associated with Increased Mortality in a Hospital Setting

ABSTRACT Bacteremia caused by methicillin-resistant Staphylococcus aureus (MRSA) USA600 has been associated with increased patient mortality. We found that USA600 MRSA exhibited significantly increased resistance to human cathelicidin LL-37 killing and daptomycin MIC creep compared to non-USA600 MRSA. Virulent health care-associated MRSA strains may coevolve innate host defense peptide and antibiotic resistances.

Resources for Infection Prevention and Control on the World Wide Web

This review summarizes infection prevention resources on the Internet. Web sites are presented in 8 categories: guidelines, policies, and regulatory bodies; health care-associated infection and multidrug-resistant organisms; surveillance, reporting, and initiatives; antibiotic use; employee health; long-term care facilities; facility and environmental infection control; and professional societies, educational opportunities, and listserves. For example, links to the National Surgical Quality Improvement Program and National Healthcare Safety Network reports are provided among resources for infection surveillance, reporting, and initiatives. A link to guidelines for infection prevention in health care workers is listed with other information regarding employee health. The Web address for the Society for Healthcare Epidemiology of America guidelines for infection control in long-term care facilities is listed with resources for long-term care facilities. Guidelines for construction and environmental services are summarized with other information regarding facility and environmental infection control. This review summarizes the most useful and up-to-date infection prevention resources on the Internet and will simplify the search for pertinent information.

Epidemiology of community-acquired and health care-associated staphylococcus aureus pneumonia

Background: Information is limited on the descriptive epidemiology of community-acquired pneumonia (CAP) and health care-associated pneumonia (HCAP) due to Staphylococcus aureus. Methods: We retrospectively identified all patients admitted to a large urban US hospital between January 2005 and May 2008 with pneumonia and positive blood or respiratory cultures for S. aureus within 48 hours of admission. Patients were designated as having CAP or HCAP based on established criteria, and methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus (MSSA) pneumonia based on results of initial cultures. Appropriateness of initial therapy was based on whether antibiotic coverage was provided for MRSA or MSSA. Results: The study sample consisted of 270 patients hospitalized for S. aureus pneumonia: 142 (53%) with HCAP and 128 (47%) with CAP. Sixty-one percent of HCAP patients and 43% of CAP patients had MRSA. Demographic and clinical characteristics of MRSA and MSSA patients were similar in both CAP and HCAP. Most HCAP patients received appropriate initial antibiotic therapy (78% for MRSA and 75% for MSSA; P = 0.69); MRSA CAP patients, however, were much less likely to receive appropriate initial therapy (40% vs 59% for MSSA CAP; P = 0.05). USA100 and USA300 strains were present in 55% and 16% of all patients with MRSA HCAP; corresponding percentages for MRSA CAP were 42% and 45%, respectively. Conclusions: Methicillin-resistant S. aureus is an important pathogen in both HCAP and CAP, and simple clinical criteria do not permit early identification of patients with MRSA versus MSSA pneumonia. Fewer than one half of patients with MRSA CAP receive appropriate initial antibiotic therapy.